The present invention relates to a method for winding a paper web, in which method the web is longitudinally divided into slit webs of desired widths and the slit webs are wound into rolls about roll cores or similar centers at a winding station and in which method the web is severed by means of a web-severing device in conjunction with the roll set change of the winding operation.
The invention also concerns an apparatus for use in paper web winding, said apparatus including slitter assemblies for longitudinally dividing the web into slit webs of desired widths and a winding station for winding the slit webs into rolls and a web-severing device for cutting the web.
In the art of papermaking, a variety of different winder constructions are known for specific applications. One winder embodiment is described in FI Patent No. 91383 disclosing a so-called center-reeler-type slitter-winder apparatus. Various types of winders are also known from slitter constructions, one embodiment being described in FI Patent No. 74260, for instance.
In the international patent application publication WO96/37429, there is disclosed a winder apparatus suited for winding a paper web immediately at the end of a papermaking process or, alternatively, for being integrated with a Pope winder of a papermaking machine. The apparatus comprises slitter means and one or two winding stations for winding webs slit from a machine-wide web. During a roll set change, this kind of device permits the web slitting operation to be temporary halted or the slit web to be severed individually. Cited publication also teaches the possibility of using a plurality of winding stations. One problem hampering this prior-art embodiment is that the web must be dumped into the pulper for a certain time during a roll set change and slitting width adjustment operation. On the other hand, further problems arise as broke will result for some time during roll set change due to the fact that driving the slitter blades into a new position unavoidably takes a certain time during which no usable web is produced.
EP application publication 0380438 discloses a web slitter and groover system for forming first and second spaced circular grooves in a roll product, said system including first and second web cutting assemblies alternately and sequentially movable to form web segments of diminished width along spaced portions thereof which, when wound, form the grooves.